An axial rotor portion of the generic type for a turbine is known, for example, from laid-open specification DE 1 963 364 A1. The rotor portion, which is formed by a rotor disk, is equipped with retainer grooves running in the axial direction for rotor blades of the turbine, with an endlessly encompassing locating groove for sealing plates being provided on the end face. The sealing plates which sit therein block displacement of the rotor blades along the retainer grooves and thereby fix the latter. Each sealing plate is in this case secured against loss by a screw.
The sealing plates moreover form a sealing ring, as viewed in the circumferential direction. The sealing ring separates a first space between the sealing plate and the end face of the rotor disk from a second space located on the other side of the sealing plate. During operation, cooling air flows through the first space, preventing thermal overloading of the blade root and of the outer rim of the rotor disk.
A disadvantage of the known apparatus is the use of a screw for securing the sealing plates against displacement in the circumferential direction. On account of the alternating thermal loading which occurs between operation and stationary state and on account of the hot gas which flows through the turbine, problems relating to corrosion and strength in the screw fastening can arise. Under certain circumstances, these cannot be resolved in a specified manner. In this case, the screw is drilled out, this operation being carried out as a rule on the rotor which still lies in the lower housing half of the gas turbine. It may be the case that swarf falls into the lower housing half in the process, which can bring about undesirable contamination during subsequent operation.
Furthermore, FR 2 524 933 discloses securing rotor blades against axial displacement, these rotor blades being retained by means of a plate which is displaceable in the circumferential direction. The arrangement which is shown therein is not suitable, however, for sealing off a space close to the disk in relation to a space present on the other side of the plate. There is therefore the risk here of thermally-induced damage to the blade root and rotor disk rim.
Furthermore, laid-open specification DE 30 33 768 A1 discloses a rotor sub-assembly for a rotor disk of a turbine which has a single-piece sealing ring for axially securing rotor blades. On account of the fact that the sealing ring has a single-piece construction, it is only suitable, however, for aircraft gas turbines, since these are assembled by alternately stacking rotor and stator components in the axial direction. Stationary gas turbines, by contrast, are assembled from two housing halves which encompass the completely installed rotor. The single-piece sealing ring in DE 30 33 768 A1 is hooked to the turbine disk in the manner of a bayonet connection.
Furthermore, US 2004/0081556 A1 discloses a gas turbine blade of the generic type having a blade root, a platform and a main blade part. The platform extends from a leading edge to a trailing edge, with respect to the hot gas which flows through the gas turbine in the axial direction. The platform has a trailing edge which runs in the circumferential direction of the turbine disk and which protrudes beyond the axial width of the turbine disk in the manner of an eave. A plurality of structural elements which influence the cooling-air flow are provided on the underside of the trailing edge of the platform.
With an increasing advance in technology and new demands on the performance and service life of gas turbines, there is the need to provide new designs which, in spite of technically more demanding boundary conditions, continue to have the desired service life.